By using a new system that combines a confocal scanning laser microscope (CSLM) and a rheometer, we observed the structural change and measured the shear stress simultaneously in an immiscible polymer blend. The blend used is composed of a liquid crystalline plolymer (LCP) and a petroline mineral oil (PMO). When subjected to an external electric field, we observed a change from an LCP‐droplet‐dispersed structure to a network structure, corresponding to an increase of the shear stress. © 2004 American Institute of Physics